This invention relates to the metallurgical bonding of metal components and, more particularly, to the use of a combination of heating and impacting to provide a forged joint.
The technique of pressure bonding or welding together cooperating metal components is most advantageously conducted by localized heating of the cooperating surfaces followed by pressing of the surfaces together. In order to provide for such localized or controlled depth heating and still allow for pressing of the heated portions together, known methods have used high frequency resistance heating to heat the joint surfaces rapidly to a shallow depth while the surfaces to be joined are in contact one with the other. The high frequency resistance current is introduced with electrical contacts, such as of copper. When the electrical power is applied, the current then travels along each face, thus heating the entire joint length. When a preselected bonding temperature has been reached, application of electrical power is terminated and the components are pressed together. Such a method and its associated apparatus is shown in one form in U.S. Pat. No. 3,591,757 -- Rudd patented July 6, 1971.
Although such known methods can produce joints with parent metal mechanical properties, they are amenable only to specimens with rectangular cross section. Since such processes rely on close part-to-power contact fit-up, difficulties have arisen in connection with reproducability when bonding non-rectangular cross sections, for example an airfoil cross section.